1. Field of the Invention
The present invention relates to a wireless communication system, and more particularly, to a radio measurement procedure for station (STA) statistics in a wireless communication system and a device supporting the radio measurement procedure.
2. Description of the Related Art
With development of information communication technologies, a variety of wireless communication technologies have been developed. A wireless LAN (WLAN) is a technology permitting wireless access to Internet in specific service areas such as home or companies or air planes by the use of portable terminals such as a personal digital assistant (PDA), a laptop computer, and a portable multimedia player (PMP) on the basis of a radio frequency technology.
These days, thanks to the increased availability of WLANs, portable terminal users such as laptop computer users are able to perform their tasks with increased mobility. For example, a user can take his laptop computer from his desk into a conference room to attend a meeting and still have access to his local network to retrieve data and have access to the Internet via one or more modems or gateways present on the local network without being tethered by a wired connection. Similarly, business travelers commonly use their portable terminals to gain access to their email accounts, to check if there is any unread email, and to read and send email.
In the initial WLAN technology, a data rate of 1 to 2 Mbps was supported by the use of frequency hopping, spread spectrum, and infrared communication using a frequency of 2.4 Ghz in accordance with the IEEE 802.11. In recent years, with the development of the wireless communication technology, 54 Mbps in maximum can be supported by applying the orthogonal frequency division multiplex (OFDM) technology, etc. to the WLAN. In addition, the IEEE 802.11 has developed or is developing wireless communication technologies for improvement in quality of service (QoS), compatibility of an access point (AP) protocol, security enhancement, radio measurement or radio resource measurement, wireless access in vehicular environment, fast roaming, mesh network, inter-working with external networks, wireless network management, and the like.
In the radio resource measurement procedure, a STA observes the radio link performance and the radio environment and/or collects data measured by another STA. The radio resource measurement procedure is performed to understand the radio environment. For example, the STA can locally measure the radio environment or can request another STA for measuring one or more elements. The STA can receive a request for measuring one or more elements from another STA and can inform the STA of the measurement result. The radio measurement data acquired in the procedure can be used to manage the STA and can be provided to a higher protocol layer for various applications.
A variety of means can be used for the radio resource measurement in the wireless network. For example, beacon frames or measurement pilots having a predetermined format can be used for the radio resource measurement. A method of calculating a channel load or a noise histogram may be used therefor. A method using statistical information of STAs can be used for the radio resource measurement. In this case, values recorded in various counters of the STA or BSS (Basic Service Set) average access delay time can be contained in the statistical information.